[Ada] Fix -gnatR3 output for dynamically constrained record

[Ada] Fix -gnatR3 output for dynamically constrained record

2018-12-11  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* gcc-interface/decl.c (gnat_to_gnu_entity): Add
	gnat_annotate_type local variable initialized to Empty.
	<E_Record_Subtype>: Set it to the Cloned_Subtype, if any.  For
	types, back-annotate alignment and size values earlier and only
	if the DECL was created here; otherwise, if gnat_annotate_type
	is present, take the values from it.
	(gnat_to_gnu_field): Add gnat_clause local variable.  If a
	component clause is present, call validate_size only once on the
	Esize of the component.  Otherwise, in the packed case, do not
	call validate_size again on the type of the component but
	retrieve directly its RM size.
	(components_to_record): Minor tweak.
	(set_rm_size): Remove useless test.
	* gcc-interface/trans.c (gnat_to_gnu): Do wrap the instance of a
	boolean discriminant attached to a variant part.

From-SVN: r267008